Radiolabelling of medical devices with Y-90: based upon adsorption induced by sonication

Chemical deposition of 90Y onto medical devices can be accomplished by adsorption using an ultrasonic bath, controlled pH, and chemical purity. The rate of deposition can be controlled to provide a uniform activity profile. After a heating cycle, the leaching rate, without any additional coating, is remarkably low (< 1%) in normal saline (0.9%). This method may be used with other suitable diagnostic or therapeutic isotopes. Ultrasonic irradiation causes the 90Y to accumulate (likely by nucleation induced by the irradiation) onto the metal surface of the stent. Optimal pH ranges from 7-9. This is controlled by minimal addition of a buffer (0.1% NaHCO3). There is also an apparent limit to the amount of Y-90 which can be deposited per cm2 of metal surface (∼100 mCi/cm2). The uniformity of the coating can be controlled by varying the process parameters volume, concentration, time of deposition, temperature and ultrasonic intensity. This process can be used in individual or batch processing. It also allows coatings of potentially important therapeutic isotopes without the use of ion implanter technology which is more expensive and less efficient. (author)